[PATCH] D119409: [C++20] [Modules] Remain dynamic initializing internal-linkage variables in module interface unit

Fri Feb 18 16:32:28 PST 2022

dblaikie added a comment.

In D119409#3332476 <https://reviews.llvm.org/D119409#3332476>, @urnathan wrote:

> In D119409#3332313 <https://reviews.llvm.org/D119409#3332313>, @dblaikie wrote:
>
>> 
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> That's interesting data.  I guess one could emit the out-of-line bodies into their own sections, and then rely on linker section GC to elide them in the static link.

Yep, that's what I did - they were emitted weak_odr (weak linkage in ELF semantics) - but I was mostly interested in the object size reduction in fully statically linked binaries, so producing redundant or unused descriptions was hurting that goal. (& yeah, shared library issues are a whole other bucket I didn't even consider/evaluate)

> Richard and I discussed taking advantage of this kind of new home location, certainly for key-less polymorphic classes.  I was against it as it was more work :) Blame me.

Ah, possibly. ( https://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20170710/198206.html - seems I've had this question for a while (pinged this thread a few times over the years) & never got a clear answer from Richard at least... (@rsmith ?) - but I vaguely remember discussing it, maybe in some more ad-hoc conversation that didn't make it onto the mailing list... )

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